This is a brutal way of uninstalling an extension. It will remove ALL of your extensions and themes. We will provide more precise uninstall instructions later (or feel free to submit them so we can post them here)

Close Thunderbird

Determine where you've installed Outbox - either in your profile or in the Thunderbird program directory. This determines the value of <wherever>.

Back up the directory where you're about to make changes, in case something goes wrong

Remove outbox.jar from <wherever>\thunderbird\chrome

Remove chrome.rdf from <wherever>\thunderbird\chrome

Remove the overlayinfo directory from <wherever>\thunderbird\chrome

That should be it - you're now ready to start Thunderbird again. If it doesn't work, feel free to drop us an email, but don't hold us responsible!